Smectic phases in ionic liquid crystals

TL;DR

This paper investigates the phase behavior of ionic liquid crystals using density functional theory and Monte Carlo simulations, revealing a novel smectic-A phase with unique layered structures.

Contribution

It introduces the discovery of a new wide smectic-A phase in ionic liquid crystals, characterized by alternating particle orientations, expanding understanding of their phase behavior.

Findings

Identification of a new smectic-A phase $S_{AW}$

Layer spacing larger than in ordinary smectic-A phase

Alternating layers of differently oriented particles

Abstract

Ionic liquid crystals (ILCs) are anisotropic mesogenic molecules which carry charges and therefore combine properties of liquid crystals, e.g., the formation of mesophases, and of ionic liquids, such as low melting temperatures and tiny triple-point pressures. Previous density functional calculations have revealed that the phase behavior of ILCs is strongly affected by their molecular properties, i.e., their aspect ratio, the loci of the charges, and their interaction strengths. Here, we report new findings concerning the phase behavior of ILCs as obtained by density functional theory and Monte Carlo simulations. The most important result is the occurrence of a novel, wide smectic-A phase $S_{AW}$, at low temperature, the layer spacing of which is larger than that of the ordinary high-temperature smectic-A phase $S_{A}$. Unlike the ordinary smectic $S_A$ phase, the structure of the $S_{AW}$ phase consists of alternating layers of particles oriented parallel to the layer normal and oriented perpendicular to it.